4-oxo-4h-1-benzopyran and 4-oxo-4h-1-thiabenzopyran compounds

ABSTRACT

There are described 4-oxo-4H-1-benzopyran and 4-oxo-4H-1thiabenzopyran compounds having a group -CONROH in the 2position, R representing hydrogen, alkyl, phenyl or phenylalkyl, provided that the compounds are not of formula XXXI, in which Ra is hydrogen or chloride, and pharmaceutically acceptable derivatives thereof. The compounds are indicated for use in the treatment of asthma.   D R A W I N G

United States Patent [191 Cairns et al.

[451 De ial, 1974 4-OXO-4H-l-BENZOPYRAN AND 4-OXO-4H- 1 -THIABENZOPYRAN COMPOUNDS Inventors: Hugh Cairns; Norman Harold Rogers, both of Loughborough,

England Assignee: Fisons Limited, London, England Filed: Sept. 26, 1972 Appl. No.: 292,453

Related U.S. Application Data Continuation-in-part of Ser. No. 260,205, June 6, 1972, abandoned.

Foreign Application Priority Data [56] References Cited UNITED STATES PATENTS 3,629,290 12/1971 Cairns et al; 260/345.2 3,710,459 l/l973 Hazard et al. 260/327 TH 3,720,690 3/1973 King et al. 260/345.2

Primary Examiner-Henry R. Jiles Assistant Examiner-C. M. S. Jaisle Attorney, Agent, or Firm-Wenderoth, Lind & Ponack [5 7 ABSTRACT There are described 4-0x0-4l-l-l-benzopyran and 4-oxo-4l-I-l-thiabenzopyran compounds having a group -CONROH in the 2-position, R representing hydrogen, alkyl, phenyl or phenylalkyl, provided that the compounds are n06 of formula XXXI,

Ra 7 in which Ra is hydrogen or chloride, and pharmaceutically acceptable derivatives thereof. The compounds are indicated for use in the treatment of asthma.

l l CONROH XXXI 8 Claims, No Drawings 1 4-OXO-4H-1-BENZOPYRAN AND 4-OXO-4H-l-THIABENZOPYRAN COMPOUNDS XXXI I Ra O CONROH in which Ra is hydrogen or chlorine,

and pharmaceutically acceptable derivatives thereof.

According to a preferred feature of our invention we provide compounds of formula la,

CONROH Ia Rd HORNOC l l H in which Ba and Bb represent the pair of groups: a carbon-carbon bond and CRf=CRg,

or an adjacent pair of Rb, Rc, Rd and Re represent a group of formula III,

III HORNOC Rf and Rg having the same significances as Rb, Rc, Rd and Re given in (i) above,

or one of Rb, Rc, Rd and Re represent a group of formula IV,

l IV HORNOC in which X is a carbon-carbon bond, a single linking atom or a5 or 6 membered carboxylic or a 5 or 6 membered heterocyclic ring or a hydrocarbon chain which chain may be substituted by a hydroxy group, a halogen atom or a C l to 6 alkoxy group or interrupted by a 5 or 6 membered carbocyclic or 5 or 6 membered heterocyclic ring, an oxygen atom, a sulphur atom, a nitrogen atom, an S0 or S0 group, or X is a group OX- "O- in which X is a straight or branched hydrocarbon chain which may be interrupted by a 5 or 6 membered carbocyclic or a 5 or 6 membered oxygen containing heterocyclic ring, an oxygen atom, a nitrogen atom or a carbonyl group, and which may be substituted by a hydroxy group, an alkoxy group or a halogen atom,

P, Q and T have the same significances as Rb, Rc, Rd

and Re given in (i) above,

W is oxygen or sulphur, and

R is hydrogen, alkyl, phenyl or phenylalkyl,

provided that when W is oxygen and R, R6, R0 and Re are all hydrogen Rd is not hydrogen or chlorine,

and pharmaceutically acceptable derivatives thereof.

According to our invention we also provide a process for the production of a compound I, or a pharmaceutically acceptable derivative thereof-which comprises a. reacting an ester, anhydride or acid halide of a (to be called a compound XVlll) corresponding to 4-oxo-4H-l-benzopyran or of a corresponding 4-oxo-4H-l-thiabenzopyran having a 'COOH group in the 2- position,

with a compound of formula V,

NHROH v in which R is as defined above,

b. selective dehydrogenation ofa (to be called a compound XIX) corresponding 2,3-dihydro-4-oxo-4H-L benzopyran or of a corresponding 2,3-dihydro-4-oxo- 4H-l-thiabenzopyran having a group -CONROH in the 2- position, in which R is as defined above, or

c. selective hydrogenation or hydrolysis of a (to be called a compound XXIl) corresponding 4-oxo-4H-lbenzopyran or of a corresponding 4-oxo-4H-lthiabenzopyran having a group -CONROY in the 2- position in which-R is as defined above,

and Y represents a group which is convertible to a hydrogen atom by hydrogenation or hydrolysis,

and where desired converting the compound I to a pharmaceutically acceptable derivative thereof;

More specifically we provide a process for the production of a compound of formula la, or a pharmaceutically acceptable derivative thereof,-which comprises,

a. reacting an ester, anhydride or acid halide of a compound of formula VI,

Rh 0 Ri v1 OOH Rj w in which W is as defined above,

Rh, Ri, Rj and Rk have the same significances as Rb, Rc, Rd and Re in (i) above, or

one or more adjacent pairs of Rh, Ri, Rj and Rk represent a chain COCH=C(COOH)W or a group of formula VII,

6 Ba w Bb in which W, Ba and Bb are as defined above, or an adjacent pair of Rh, Ri, Rj and Rk represent a group of formula VIII,

VII

o Rf VIII H w in which W is as defined above, and

Rf and Rg are as defined above,

or one of Rh, Ri, Rj and Rk represent a group of formula IX,

in which W, X, P, Q and T are as defined above, and

W and the proviso are as defined above,

with a compound of formula V,

b. selectively dehydrogenating a compound of formula X,

CONROH in which W and R are as defined above,

RI, Rm, Rn and R0 have the same significances as Rb, Rc, Rd, and Re as'defined in (i) above,

or one or more adjacent pairs of R1, Rm, Rn and Ro represent a chain -COCH CH(CONROH)-W- or a group of formula XI,

HORNOC B1) in which R, W, Ba and Bb are as defined above, or an adjacent pair of R1, Rm, Rn and R0 represent a group of formula XII,

HORNOC XII or one of the RI, Rm, Rn and Ro represent a group of formula XIII,

XIII HORNOC in which P, Q, T, W, R and the proviso are as defined above, or

c. selectively hydrogenating or hydrolysing a compound of formula XIV,

XIV CONROY in which W, Y and R are as defined above,

Rp, Rq, Rr and Rs have the same significances as Rb, Rc, Rd and Re in (i) above,

or one or. more adjacent pairs of Rp, Rq, Rr and Rs represent a chain -COCH%(CONROY)W, or a group of formula XV,

Ba ,xv

YORNOC l Bb in which W, R, Ba and Bb are as defined above, or an adjacent pair of Rp, Rq, Rr and Rs represent a group of formula XVI,

XVI YORNOC in which W, R, Rf and Rg are as defined above,

or one ofRp, Rq, Rr and Rs represents a group of formula XVII,

YORNOC XVII in which P, Q, T, W, Y and R are as defined above,

and the proviso is as defined above,

and where desired converting the compound of formula Ia to a pharmaceutically acceptable derivative thereof.

In process (a) the anhydride is preferably a mixed anhydride of such a type that it will cleave preferentially,

. to give the desired benzopyran or thiabenzopyran carpyridine or dimethylformamide. However when the re- I action is carried out in a non-basic solvent, e.g. dimethylformamide, an adequate proportion of an acid acceptor, e.g. triethylamine, should also preferably be present. The reaction is preferably carried out at a temperature of from about 1 5 to +20C. When an acid halide is used it may conveniently be an acid chloride. Suitable esters include those derived from alkanols containing from I to and preferably from I to 6 carbon atoms. When an ester is used the reaction may conveniently be carried out in a solvent which is inert under the reaction conditions, e.g. dimethylformamide, in the presence of a base, e.g. sodium hydroxide, and at room temperature, i.e. at about C.

In process (b) the dehydrogenation may be carried out using for example selenium dioxide, palladium black, chloranil, dichlorodicyanoquinone or sulphur. Alternatively the dehydrogenation may be carried out indirectly by halogenation followed by dehydrohalogenation, e.g. by treatment with N-bromosuccinimide or pyridinum bromide perbromide to yield the 3-bromo derivative which is subsequently dehydrobrominated.

In process (c) the group Y may be a benzyl group which may be removed by hydrogenation, e.g. using a conventional catalyst. Alternatively the group Y may be an acyl (e.g. lower acyl such as a C l to 6 alkanoyl) group which may be removed by hydrolysis.

The compounds I may be recovered from the reaction mixture using conventional techniques.

The esters, acid halides and anhydrides of the compounds XVIII, and the compounds of formula V them-- selves, are either known or may be made by methods known for the manufacture of similar known compounds. Thus the anhydrides of compounds XVIII may be made by conventional techniques, e.g. by reaction of an acid halide of one of the acids with the other acid, e.g. the reaction of a sulphonyl chloride or an alkyl chloroformate with theacid compound XVIII. The reaction may be carried out under the conditions described above for process (a).

Compounds XIX may be made by selective hydrogenation of a corresponding compound I, or of a suitably protected derivative thereof. 2,3-Dihydro-4-oxo-4H-lbenzopyran-Z-carbohydroxamic acids may also be made by cyclisation of a corresponding compound (to be called a compound XX) in which a pair of groups -COCH=CHCONROM and -OM, in which M is hydrogen or an alkali-metal and R is as defined above, are attached to ortho positions on a benzene nucleus,

LII

for example by treatment of the compound XX with a base or acid in a solvent which is inert'under the reaction conditions.

The compounds XXX may be made by reacting a compound (to be'called a compound XXI) in which a pair of groups -COCH=CHCOORy (Ry being an ester forming, e.g. a C l to 6 alkyl, group) and -OH. are attached to ortho positions on a benzene nucleus,

with a compound of formula V.

The compounds XXII may be made by conventional techniques from known starting materials and compound l. Compounds XXI may be made by reacting an appropriate phenolic compound with maleic anhydride.

Some of the groups P, Q, .R and Rb and Rs may be affected by the reaction conditions described above. Where necessary or desirable therefore the reaction may be carried out using protected derivatives of the reagents.

It will be appreciated that the group CONHOl-I, which is a preferred form of the group-CONROH, represented above may also exist in the tautomeric form .-C(OH)=NOH and this tautomeric form of the compounds I is also included in our invention.

The process described above may produce the compound I or a derivative thereof. It is also within the scope of this invention to treat any derivative so produced to liberate the free compound I, or to convert one derivative into another. Suitable derivatives include salts and notably water-soluble salts. Salts which may be mentioned include basic addition salts, e.g. ammonium salts, ammonium salts, e.g. derived from mono-, diand tri-Iower alkyl amines, alkali-metal and alkaline-earth metal salts, notably the sodium salt.

According to a further feature of our invention we provide a process for the production of a pharmaceutically acceptable salt of a compound Iwhich comprises treating a compound I, or another salt thereof, with an appropriate base of salt containing an available pharmaceutically acceptable cation.

The compounds I, and pharmaceutically acceptable derivatives thereof, are useful because they possess pharmacological activity in animals; in particular they are useful because they inhibit the release and/or action of pharmacological mediators which result from the in vivo combination of certain types of antibody and specific antigen, e.g. the combination of reaginic antibody with specific antigen. (See Example A be-- low).

In man, both subjective and objective changes which result from the inhalation of specific antigen by sensitised subjects are inhibited by prior administratio n'of the new compounds. Thus the new compounds are useful in the treatment of asthma, e.g. allergic asthma. The new compounds are also useful in the treatment of socalled intrinsic asthma (in which no sensitivity to extrinsic antigen can be demonstrated). The new compounds are also of use in the treatment of other conditions in which antigen-antibody reactions are responsidesired. However, in general, satisfactory results are obtained when the compounds are administered at a dosage of from 0.1 to mg per kg of animal body weight in the test set out in Example A. For man the ble for disease, for example, allergic rhinitis and urticatotal daily dosage is in the range of from about 1 mg to 3,500 mg preferably to 1,500 mg and more preferably to 1,000 mg which may be administered in divided doses from 1 to 6 times a day or in sustained release form. Thus unit dosage forms suitable for administration (by inhalation or oesophageally) comprise from about 0.17 mg to 600 mg of the compound admixed with a solid or liquid pharmaceutically acceptable diluent or carrier.

The compounds 1, and pharmaceutically acceptable derivatives thereof, may be administered by conventional techniques, preferably in admixture with a major proportion of a pharmaceutically acceptable adjuvant, diluent or carrier. Specifically the compounds may be administered by inhalation as a liquid or powder composition, e.g. a powder composition containing a compound 1 having a particle size of from 0.1 to 10 microns and a diluent such as lactose, or oesophageally as a tablet or capsule.

As a preferred group of compounds we provide those of formula 10,

Ic RV CONROH on cacn o OCH 2 CONROH in which W and R are as defined above.

Rb, Rc, Rd and Re preferably each contain up to 10 and more preferably up to 6 carbon atoms. Rb, Rc, Rd and Re may be, for example, hydrogen, alkyl C l to 10. chlorine, bromine, fluorine, hydroxy, alkenyl C2 to 10, phenyl, alkoxy C l to 10, alkenyloxy C2 to 10, or phenyl-alkoxy, the alkoxy of which is C 1 to 4; hydroxyalkyl C l to 10, hydroxy-alkoxyC 1 to 10,alkoxy-alkyl in which the alkoxy and alkyl groups are both C l to 10, or alkoxy-alkoxy in which both alkoxy groups are C l to 10. When one of Rb, Rc, Rd and Re represents a group substituted by a heterocyclic ring the ring may be, for example, a tetrahydrofuran ring.

As a preferred group we provide those compounds in which Rb, Rc, Rd and Re are selected from hydrogen; alkyl, e.g. propyl; alkoxy, e.g. methoxy or pentyloxy; alkenyl, e.g. allyl; and hydroxy.

W is preferably oxygen.

R is preferably alkyl C l to 6, e.g. methyl; phenyl, or more preferably hydrogen.

Preferred values of X are a carbon-carbon bond, CH CHOH-, C(R) CO-, CH- (COOH)- and esters thereof, C(=CCI,)-, CHC H N, -NH, S, SO- SO and O, R being an alkyl C 1 to 6 group,

a saturated or unsaturated, straight or branched C 2 to 10 polymethylene chain which may carry one or more OH or C 1 to 6 alkoxy groups, halogen atoms or carbonyl oxygen substituents and which may have the chain thereof interrupted by one or more oxygen or nitrogen atoms.

Preferred values of X are a saturated or unsaturated, straight or branched C 2 to 10 polymethylene chain which may carry one or more hydroxy groups. C 1 to 6 alkoxy groups, halogen atoms or carbonyl oxygen substituents and which may have the chain thereof interrupted by one or more oxygen or nitrogen atoms.

The invention is illustrated, but in no way limited by the following Examples.

EXAMPLE 1 a. 6,8-Di-t-Butyl-4-oxo-4l-ll benzopyran-ZZ-carbohydroxamic acid 6,8-Di-t-Butyl-4-oxo-4l-l-l benzopyran-Z-carboxylic acid (18.12g) was dissolved in anhydrous pyridine (300 ml) and the stirred solution was then cooled to l0C. Benzene-sulphonyl chloride (7.70 ml) was added dropwise over 10 minutes, after which the temperature was allowed to rise to a maximum of 0C and maintained for 30 minutes. The mixed sulphonic acid anhydride began to crystallize out. The stirred mixture was again cooled to 10C and a solution of hydroxylamine hydrochloride (4.17g) in anhydrous pyridine (15 ml) was added dropwise. The mixture was stirred for 2 hours at 0C and gradually allowed to attain room temperature overnight. The resulting clear solution was evaporated to dryness in vacuo. The oily residue was dissolved in water and acidified to pH4 with hydrochloric acid. The resulting white precipitate was extracted into ether and the latter was washed with dilute hydrochloric acid, water, cold dilute sodium bicarbonate, water, dried over magnesium sulphate and evaporated to dryness in vacuo to give a cream solid. This solid was crystallized from ethyl acetate to yield 6,8-di-t-butyl-4-oxo-4H-1- benzopyran-2-carbohydroxamic acid as a white crystalline solid (7.2g) mp l84.5 185C. Analysis:

Found: C, 68.1; H, 7.4; N, 4.2%

C H NO requires: C, 68.1; H, 7.3; N, 4.4%

Spectral Confirmation The molecular weigt of 317 was confirmed by mass spectroscopy.

The infra red spectrum displayed peaks at 3250 and 3120 cm for the NH and OH stretching frequencies.

The nmr spectrum in deuterochloroform displayed the 3-proton of the benzopyran ring system as a sharp singlet at 2.88 'r.

b. 6,8-Di-t-Butyl-4-oxo-4H-l-benzopyran-Z-carbohydroxamic acid sodium salt.

6,8-Di-t-Butyl-4-oxo-4l-l-1-benzopyran-2-carbohydroxamic acid (3.7g), sodium bicarbonate (0.99g) and water ml) were heated on a steam bath for 1 hour until complete dissolution had occurred and effervescence had ceased. The resulting yellow solution was freeze dried to give 6,8-di-t-butyl-4-oxo-4H-lbenzopyran-Z-carbohydroxamic acid sodium salt as a yellow powder (4.0g).

EXAMPLE 2 8-Allyl-5-(3-methylbutoxy)-4-oxo-4H-1-benzopyran- 2carbohydroxamic acid sodium salt a. 8-Allyl-5-( 3-methylbutoxy)-4-oxo-4H- l -benzopyran- 2-carbohydroxamic acid Benzene sulphonyl chloride (15.4 ml) was added dropwise over a period of 15 minutes to a stirred solution of 8-allyl-5-(3-methylbutoxy-)-4-oxo-4H-lbenzopyran-2-carboxylic acid (380g) in anhydrous pyridine (500 ml) maintaining the temperature between and 10C. The solution was maintained at 0C for a further 45 minutes and cooled again to l0C. A solution of hydroxylamine hydrochloride (834g) in anhydrous pyridine (30 ml) was added to the above solution and the mixture was stirred for 3 hours. The pyridine was removed in vacuo and the residual oil was triturated with water, followed by acidification to pH 4.0 with concentrated hydrochloric acid. A yellow, fluffy precipitate and a sticky, brown solid were ob tained. The former was decanted from the latter and was found to be starting material. The sticky, brown solid was collected and triturated with acetone and water to a brownish solid, which was collected, washed with water and dried in vacuo (27*.7g), mp l68-170C (decomp). This material was treated with charcoal and twice crystallized from ethanol/water to give 8-allyl-5- (3-methylbutoxy)-4-oxo-4H-l-benzopyran-Z-carbohydroxamic acid as a pale yellow, crystalline solid, which was collected and dried in vacuo (8.1 g) mp 179.5 180C (decomp).

Analysis:

Found: C, 65.1; H, 6.5; N, 4.3% C l-l ,NO,-, requires: C, 65.2; H, 6.4; N, 4.2%

Spectral Confirmation Molecular weight 331 by mass spectrometry.

The infra red spectrum revealed an N-H and OH. str. at 3200 cm".

The nmr spectrum in hexadeuterodimethylsulphoxide displayed the 3-proton of the benzopyran ring system at 3.421- and the NH and OH protons at 0.45'r and l .457.

b. 8-allyl-5-(3-methylbutoxy)-4-oxo-4H-l-benzopyran-2- carbohydroxamic acid sodium salt 8-Allyl-5-(3rmethylbutoxy)-4-oxo-4H-1- benzopyran-2-carbohydroxamic acid (2.6g) was dissolved in cold aqueous 1N sodium hydroxide solution (7.8 ml) followed by dilution with water ml). The resulting yellow solution was filtered and the filtrate was freeze dried to give 8-al1yl-5-(3-methylbutoxy)-4- oxo-4l-l-lbenzopyran-2-carbohydroxamic acid sodium salt dihydrate (2.8 g) as a yellow powder. Analysis:

Found: C, 56.7; H, 6.2; N, 3.9%

C H NO Nalll O requires: C, 56.7; 1-1, 6.1; N,

Spectral Confirmation The nmr spectrum in hexadeuterodimethylsulphox- LII ide revealed the 3-proton of the benzopyran ring system at 3.577.

EXAMPLE 3 5 -Hydroxy-8-n-propyl-4-oxo-4H-1-thiabenzopyran-2- carbohydroxamic acid a. Ethyl 5-hydroxy'8-n-propyl-4-oxo-4H- l -thiabenzopyran-2- carboxylate Sodium 5-(3-methylbutoxy)-8-n-propyl-4-oxo-4H-l thiabenzopyran-2-carboxylate (15.0g) was refluxed in saturated, anhydrous ethanolic hydrogen chloride (200 ml) for 20 hours. The solution was evaporated to dryness and the solid state residue was triturated with water. The solid was filtered off, washed with water and dried. This material was treated with activated charcoal and crystallized from ethanol to give ethyl 5-hydroxy'8- n-propyl-4-oxo-4H1-thiabenzopyran-2-carboxylate (8.1g) as yellow plates, mp 8789C.

Analysis:

Found: C, 61.1; H, 5.6% C H O S requires: C, 61.6; H, 5.5%

Spectral Confirmation The molecular weight was shown to be 292 by mass spectroscopy. The i.r. spectrum displays a very intense ester carbonyl stretching frequency at 1800 cm with the 4-oxo carbonyl stretch at 1620 cm". The nmr spectrum in deuterochloroform reveals two sharp singlet resonances for the 3-proton of the benzopyran ring system and the phenolic proton at 2.437 and 0.36'r respectively.

b. 5-Hydroxy-8-n-propyl-4-oxo-4H- 1 -thiabenzopyran-2- carbohydroxamic acid Ethyl 5-hydroxy-8-n-propyl-4-oxo-4H-1- thiabenzopyran-2-carboxylate (7.0g; 0.019 mole) was dissolved in ethanol ml) and a solution of freshly prepared hydroxylamine in ethanol (38.6 ml; contains 0.663 g; 0.019 mole of hydroxylamine) was added. An M/lO ethanolic solution of sodium hydroxide (19.3 ml; 0.019 mole) was added drop-wise to the stirred solution. After complete addition the yellow solution was Spectral Confirmation The molecular weight was shown to be 279 by mass spectroscopy. The nmr spectrum in hexadeutero-dimethylsulphoxide revealed two sharp singlet resonances at 2.71 and -0.37r for the 3-proton of the benzopyran ring system and the phenolic proton respectively.

c. Sodium -hydroxy-8-n-propyl-4-oxo-4H- 1 -thiabenzopyran-2- carbohydroxamate 5-Hydroxy-8-n-propyl-4-oxo-4H-1-thiabenzopyran- Z-carbohydroxamic acid (1.8 g; 0.00645 mole) was suspended in water ml) with stirring and 0.945N sodium hydroxide solution (6.84 ml; 0.00645 mole) was added dropwise. The resulting yellow solution was filtered and the filtrate was freeze dried to give sodium 5-hydr0xy-8-n-propyl-4-oxo-4H-l-thiabenzopyran-2- carbohydroxamate (1.8 g) as a yellow-orange powder, after drying for a further 6 hours in vacuo. Analysis:

Found: C, 49.0; H, 4.1; N, 4.15%

C H NNaO S with 5.4% water requires: C, 49.0; H,

Spectral Confirmation The nmr spectrum in hexadeuterodimethylsulphoxide revealed two sharp singlet resonances at 2.8 and 4.35r for the 3-proton of the benzopyran ring system and the phenolic portion respectively.

EXAMPLE 4 6,8-Di-t-butyl-4-oxo-4H-1-benzopyran-2-(N- phenyl)carbohydroxamic acid a. 6,8-Di-t-butyl-4-oxo-4H-l-benzopyran-2-carbony1 chloride Spectral Confirmation The infra red spectrum shows a peak at 1770 cm characteristic of an acid chloride carbonyl stretching frequency.

b. 6,8-Di-t-butyl-4-oxo-4H-1-benzopyran-2-(N-phenyl) carbohydroxamic acid N-Phenylhydroxylamine (3.7 g) and 6,8-di-t-butyl-4- oxo-4H-l-benzopyran-Z-carbonyl chloride (10 g) were mutually dissolved in dry pyridine. The resulting solution was allowed to stand at room.temperature for 2 days. The pyridine was removed in vacuo and the residue was triturated with water. The residue was extracted into chloroform and the organic layer was washed with dilute hydrochloric acid, brine, dried over anhydrous magnesium sulphate and filtered. The filtrate was evaporated to dryness to yieldd a fawn coloured solid. This solid was crystallized, with charcoal treatment, from methanol/water to give 6,8-di-t-butyl- 4-oxo-4H- l -benzopyran-2-(N-phenyl )carbohydroxamic acid (2.5 g) mp 200-201C.

Analysis:

Found: C, 73.4; H, 7.2; N, 3.55% C H NO requires: C, 73.26; H, 6.92; N, 3.56%

Spectral Confirmation The nmr spectrum in deuterochloroform revealed the resonance of the 3-proton of the benzopyran ring as a sharp singlet at 3.581.

EXAMPLE 5 6,8-Di-t-butyl-4-oxo-4H-l-benzopyran-2-(N- methyl)carbohydroxamic acid a. 6,8-Di-t-butyl-4-oxo-4H-l-benzopyran-2-(N- methyl )carbohydroxamic acid N-Methylhydroxylamine hydrochloride (4.6 g; 0.055

mole) and 6,8-di-t-butyl-4-oxo-4H-1-benzopyran-2- carbonyl chloride (16 g; 0.05 mole) were mutually dissolved in dry pyridine and allowed to stand at room temperature for 3 days. The pyridine was removed in vacuo and the residual oil was dissolved in chloroform. The latter was washed with 2N hydrochloric acid, brine, dried over anhydrous magnesium sulphate and filtered. The filtrate was evaporated to dryness to yield a solid. This solid was triturated with hot aqueous sodium bicarbonate solution, then filtered off. Crystallisation from chloroform/petrol (-80) gave pure 6,8- di-t-butyl-4-oxo-4H-1-benzopyran-2-(N-methy1)carbohydroxamic acid (6.2 g), mp 176.5 177.5C. Analysis:

Found: C, 68.8; H, 7.9; N, 4.5%

C H NO requires: C, 68.86; H, 7.60; N, 4.23%

Spectral Confirmation The nmr spectrum in deuterochloroform revealed sharp singlet resonances from the N-methyl group at 5.51r and the 3-proton of the benzopyran ring at 3.481.

b. Sodium 6,8-di-t-butyl-4-oxo-4H-1-benzopyran-2-(N-methyl) carbohydroxamate 6,8-Di-t-butyl-4-oxo-4H-l-benzopyran-2-(N-methyl) carbohydroxamic acid (5.0g; 0.0152 mole) was suspended in water 10 ml). Standard aqueous sodium hydroxide solution (0.945N, 16.0 ml; 0.0152 mole) was added resulting in a deep yellow solution. The latter was freeze dried to give sodium 6,8-di-t-butyl-4-oxo- 4H-l-benzopyran-2-(N-methyl)carbohydroxamate dihydrated as a yellow powder. Analysis:

Found: C, 59.3; H, 7.2; N, 3.5%

C H NNaO .2H O: C, 59.3; H, 7.2; N. 3.6%

EXAMPLE 6 8-Allyl-5-( 3-methylbutoxy )-4-oxo-4H- l -benzopyran- Z-(N-phenyl)carbohydroxamic acid a. 8-Allyl-5-( 3-methylbutoxy )-4 -oxo-4H- l -benzopyran- 2-carbonyl chloride 8-Allyl-5-( 3-rnethylbutoxy)-4-oxo-4H-1- benzopyran-2-carboxylic acid (24.8g; 0.08 mole) was suspended in a mixture of sodium dried benzene (200 ml) and thionyl chloride (12.8 g; 0.20 mole) and heated under reflux until complete dissolution occurred (approximately 3 hrs). The resulting solution was evaporated under reduced pressure to remove the solvent and the excess thionyl chloride. The yellow oil obtained crystallized from petrol (40-60) to give pure 8-allyl-5-(3-methylbutoxy)-4-oxo-4H-l-benzopyran-Z- carbonyl chloride (17.5g). mp 63.566C.

Spectral Confirmation The mass spectrum confirmed the molecular weight and also revealed isotopic abundance of chlorine (m/e 334 and 336 for molecular ions in the ratio 3:1). The infra red spectrum displayed a carbonyl stretching frequency at 1750 cm characteristic of an acid chloride.

b. 8-Allyl-5-( 3-methylbutoxy )-4-oxo-4H- 1 -benzopyran- 2-(N-phenyl)carbohydroxamic acid N-Phenylhydroxylamine (10.9g; 0.1 mole) and 8- allyl--(3-methylbutoxy)-4-oxo-4H-l-benzopyran-Z- carbonyl chloride (33.4g; 0.1 mole) were mutually dissolved in dry pyridine 100 ml) and allowed to stand at room temperature for 4 hours. The pyridine was removed in vacuo and the residual oil was extracted into chloroform. The latter was washed with dilute hydrochloric acid, water, dried over magnesium sulphate and filtered. The filtrate was then evaporated to dryness and the resulting oil was crystallized from benzene/petrol (6080) to .give 8-allyl-5-(3 methylbutoxy)-4- oxo-4H-1-benzopyran-2-(N-phenyl)carbohydroxamic acid (6.8 g) as a white solid, mp l27-l29C. Analysis:

Found: C, 70.8; H, 6.2; N, 3.4%

C H NO requires: C, 70.74; H, 6.18; N, 3.44%

Spectral Confirmation The mass spectrum confirmed the molecular weight of 406. The nmr spectrum in deuterochloroform revealed the 3-proton of the benzopyran ring at 3.427 and the N-phenyl group together with the 6- and 7- protons at 31'.

EXAMPLE 7 8-Allyl-5-( 3-methylbutoxy )-4-oxo-4H- l -benzopyran- 2-(N-methyl) carbohydroxamic acid 8-Allyl-5-(3-methylbutoxy)-4-oxo-4H-lbenzopyran-Z-carbonyl chloride (16.7 g; 0.05 mole), and N-methylhydroxylamine hydrochloride (4.60 g; 0.055 mole) were mutually dissolved in dry pyridine 55 ml) and stirred at room temperature overnight. The solution was evaporated to dryness and the residue was triturated with dilute hydrochloric acid. The resulting solid was filtered off, washed with water and dried. (17.8 g). This was crystallized from benzene to give a solid, which was heated with aqueous sodium bicarbonate solution and filtered off. The white solid collected was washed with water and dried in vacuo (1 1.0g). The latter was crystallized from benzene to give pure 8- allyl-5-(3-methylbutoxy)-4-oxo-4H-l-benzopyran-Z- (N-methyl)carbohydroxamic acid (10.0g) mp l55156C. Analysis:

Found: C, 66.2; H, 6.8; N, 4.0%

C H NO requires: C, 66.07; H, 6.71; N, 4.06%

Spectral Confirmation The mass spectrum confirmed the molecular weight of 345. The nmr spectrum in deuterochloroform revealed the N-methyl resonance as a sharp singlet at 6.047 and the 3-proton of the benzopyran ring as a singlet at 3.5-r.

Sodium 8-Ally l-5-(3-methylbutoxy)-4-oxo-4H-l-benzopyran- 2-(N-methyl)carbohydroxamate -(N-methyl) carbohydroxamate EXAMPLE 8 5-Methoxy-4,l0-dioxo-4H,l0H-benzo[1,2-b:3,4-b]- dipyran-Z,8-dicarbohydroxamic acid, disodium salt dihydrate Diethyl 5-methoxy-4,l0-dioxo-4H,l0H-benzo[1,2- b:3,4-b']dipyran-2,8-dicarboxylate (7.8 g; 0.02 mole) was dissolved in chloroform ml). A solution of hydroxylamine (2.64 g; 0.08 mole) in ethanol ml) was added followed by the dropwise addition of a solution of sodium hydroxide (1.6g; 0.04 mole) in ethanol (40 ml). An immediate yellow precipitate was observed. After complete addition of the sodium hydroxide solution, the mixture was stirred at room tempera ture overnight. The yellow precipitate was collected by filtration, washed with chloroform and ethanol and dried in vacuo. The yellow powder was crystallized from acetone/water twice to give pure di-sodium S- methoxy-4,10-dioxo-4H,l 0H-benzo[ l ,2-b:3,4- b]dipyran-2,8-dicarbohydroxamate dihydrate (1.0g). Analysis:

Found: C, 40.9; H, 2.7; N, 6.0%

C, H N Na O .2H O requires: C, 40.9; H, 2.7; N,

EXAMPLE 9 6,8-Di-t-Butyl-4-oxo-4H-1-benzopyran-2-carbohydroxamic acid A solution of hydroxylamine and sodium hydroxide in ethanol (40 ml) (prepared 'by mixing a solution of 6.95g of hydroxylamine hydrochloride in 100 ml ofethanol with a solution of 8.0g of sodium hydroxide in 100 ml of ethanol followed by filtration) was added dropwise to a stirred solution of ethyl 6,8-di-t-butyl-4-oxo- 4H-1-benzopyran-Z-carboxylate (6.6g; 0.02 moles) in ethanol (10 ml). An immediate yellow colour'was obtained and the solution was stirred for ten minutes. The mixture was evaporated to dryness. The residue was taken up in water and the resulting yellow solution was oxo-4H-l-benzopyran-Z-carbohydroxamic acid, mp

l84.5 C. This material was identical to that obtained by the method of Example la.

EXAMPLE 10 a. Di-sodium 5 ,5 -l (2-hydroxytrimethylene )dioxy]bis( 4-oxo-4H- l benzopyran-Z-carbohydroxamate)dihydrate A solution of hydroxylamine (2.64g; 0.08 mole) in ethanol (I60 ml) was added to a suspension of diethyl 5,5-[(2-hydroxytrimethylene)dioxy]bis(4-oxo-4H-lbenzopyran-2-carboxylate (105g; 0.02 mole) in dimethylformamide (50 ml). To this mixture, stirred at room temperature, a solution of sodium hydroxide (1.6g; 0.04 mole) in ethanol (40 ml) was added drop wise over a period of 2 hours. The mixture became yellow on addition of alkali and it was stirred overnight at room temperature. The resulting yellow precipitate was filtered off, washed with ethanol and dried in vacuo (108g). This was recrystallized from water/acetone to afford pure disodium 5,5[(2- hydroxytrimethylene )dioxy]bis( 4-oxo-4H-l benzopyran-2-carbohydroxamate )dihydrate (6.8g;

64% yield of theory). Analysis:

Found: C, 47.4; H, 3.7; N, 4.7% C H, N Na O H O requires: C, 47.7; H, 3.5; N,

Spectral Confirmation The nmr spectrum in hexadeuterodimethylsulphoxide revealed a two proton singlet resonance at 3.521- for the 3 and 3'-protons of the benzopyran rings.

b. 5 ,5 '-l 2-Hydroxytrimethylene )dioxy]bis( 4-oxo-4H- 1 benzopyran-Z-carbohydroxamic acid) sesquihydrate Spectral Confirmation The nmr spectrum in hexadeuterodimethylsulphoxide revealed a two proton singlet resonance at 3.441- for the 3 and 3-protons of the benzopyran rings.

EXAMPLE A The procedure set out below may be used to assess the effectiveness of a compound in inhibiting the release of the pharmacological mediators of anaphylaxis.

In this test, the effectiveness of the compounds in inhibiti'ng the passive cutaneous anaphylactic reaction in rats is assessed. It has been proved that this form of test gives reliable qualitative indications of the ability of the compounds under test to inhibit antibody-antigen reactions in man.

In this test method Charles River Frances/Fisons bred rats (male or female) having a body weight of from 100 to 150 gms are infected subcutaneously at weekly intervals with N, brasiliensi's larvae in doses increasing from about 2000 larvae per animal to l2000 larvae per animal in order to establish the infection. After 8 weeks the rats are bled by heart puncture and 15-20 mls. of blood collected from each animal. The blood samples are then centrifuged at 3500 rpm. for minutes in order too remove the blood cells from the blood plasma. The serum is collected and used to provide a serum containing N. brasiliensis antibody. A pilot sensitivity test is carried out to determine the least quantity of serum required to give a skin weal in control animals in the test described below of 2 cm diameter. It has been found that optimum sensitivity of rats in the body weight range 100-300 gms is obtained using a serum diluted with eight parts of physiological saline solution. This diluted solution is called antibody serum A. j

The antigen to react with the antibody in serum A is prepared by removing N. brasiliensis worms from the gut of the infested rats, centrifuging the homogenate and collecting the supernatent liquor. This liquor is diluted with saline to give a protein content of 1 mg/ml and is known as solution B.

Charles River Frances/Fisons bred rats in the body weight range 100 to 130 gms are sensitized by intradermal injection of 0.1 mls of serum A into the right flank. Sensitivity is allowed to develop for 24 hours and the rats are then injected intravenously with l ml/l00 gms body weight of a mixture of solution B (0.25 mls). Evans Blue dye solution (0.25 mls) and the solution of the compound under test (0.5 mls varying percentages of active matter). Insoluble compounds are administered as a separate intraperitoneal injection 5 minutes before intravenous administration. of solution B and Evans Blue dye. For each percentage level of active matter in the solution under test five rats are injected. Five rats are used as controls in each test. The dosages of the compound under test are selected so as to give a range of inhibition values.

Thirty minutes after injection of solution B the rats are killed and the skins removed and reversed. The in tensity of the anaphylactic reaction is assessed by comparing the size of the characteristic blue weal produced by spread of the Evans Blue dye from the sensitization site, with the size of the weal in the control animals. I

The size of the weal is rated as 0 (no weal detected, i.e. inhibition) to 4 (no difference in size of weal, i.e. no inhibition) and the percentage inhibition for each dose level calculated as:

Percent inhibition (Control group scoretrea.ted group score) X 100 Control group score wherein W is oxygen or sulphur, R is hydrogen, alkyl of l to 6 carbon atoms or phenyl,

O, a saturated or unsaturated, straight or branched C(2 to 10) polymethylene chain optionally substituted by -OH,C(1 to 6) alkoxy, halogen, carboxyl oxygen, and optionally interrupted by an oxygen or nitrogen atom, and R is an alkyl C (l to 6) group,

or X is an -OXO group in which X is a saturated or unsaturated, straight or branched C (2 to 10) polymethylene chain optionally substituted by OH, C(l to 6) alkoxy, halogen or carbonyl oxygen and optionally interrupted by an oxygen or nitrogen atom,

P. Q, T, Rb, Re, and Rd, which may be the same or different, each represent hydrogen, C (l to 10) alkyl, halogen, hydroxy, C(2 to l) alkenyl, phenyl, C(l to alkoxy, C(2 to 10) alkenyloxy, phenyl C (l to 4) alkoxy, hydroxy C (1 to 10) alkyl, hydroxy C (l to 10) alkoxy, C(] to 10) alkoxy-C(l to 10) alkyl and C(] to l0) alkoxy-C (l to 10) alkoxy, and pharmaceutically acceptable salts thereof.

in which R is as defined in claim 1.

7. A compound according to claim 1 which is 5,5'-[2- hydroxytrimethylene)dioxy]bis(4-oxo-4H-lbenzopyran-Z-carbohydroxamic acid).

8. A compound according to claim 1 in the form of a pharmaceutically acceptable salt thereof. 

1. A COMPOUND OF THE FORMULA
 2. A compound according to claim 1, wherein each of P, Q, T, Rb, Rc and Rd contains up to 6 carbon atoms.
 3. A compound according to claim 1, wherein each W is oxygen.
 4. A compound according to claim 1, wherein P, Q, T, Rb, Rc and Rd are all hydrogen.
 5. A compound according to claim 1, wherein X is an -OX''O- group as defined in claim
 1. 6. A compound according to claim 1 of formula
 7. A compound according to claim 1 which is 5,5''-(2-hydroxytrimethylene)dioxy)bis(4-oxo-4H-1-benzopyran-2 -carbohydroxamic acid).
 8. A compound according to claim 1 in the form of a pharmaceutically acceptable salt thereof. 